The present invention relates to the vulcanizing of tires. In order to assure the vulcanizing of tires, a vulcanization press is generally used. This apparatus is capable of assuring the kinematics of a mold and of contributing the heat necessary to assure the vulcanization reaction. The vulcanization press comprises the gripping means necessary for the grasping of the mold and the necessary mechanisms for opening and closing the mold. Except during the phases of the loading of a raw tire and the unloading of a vulcanized tire the mechanisms intended to assure the kinematics of the mold remain unused.
Vulcanization is a relatively slow procedure which requires that the tire be maintained in the closed mold for a period of time which varies between a few minutes and several hours depending on the size of the tire . The mechanisms of the press, which are not used for the entire time of the vulcanization process, may represent an important part of the cost of a press. As a result, there is a poor utilization of the investments.
In order to improve the profitability of the investments, the prior art already employs vulcanization systems which can be called "collective". An encaser assures the loading and unloading of a tire into and out of a mold. When this loading/unloading operation is completed, the mold leaves the encaser and remains waiting, for instance in a carousel where it is subjected to heating means in the same way as in an individual press. One example of such an installation is described in U.S. Pat. No. 3,477,100. The use of such systems is to be sure of greater interest the longer the vulcanization time.
The present invention is directed at improving these systems in which the mold does not remain attached to a press for the entire time of the vulcanization. In fact, while these systems assure a better use of the mechanisms which make it possible to provide the kinematics of the molds, they raise the problem of assuring the transfer of the heat energy for the entire time of the vulcanization. In particular, when the molds move during the vulcanization, this makes the connection which permits feeding the fluid transporting the vulcanization energy towards each mold much more complicated. In any case, the improvement in the profitability of the investment is not as great as could have been expected. For this reason, the use of such vulcanization systems has remained very marginal.
The present invention is based on the observation that it is possible to take advantage of the large heat capacity of tire molds in order to cause the transfer to the mold of the heat necessary for the vulcanization, that it is possible to effect an intense transfer of heat within a very short period of time, and that it is possible to permit the heat to pass progressively from the mold to the tire.